For many years progressive politics was represented by IVI-IPO, Independent Voters of Illinois - Independent Precinct Organization. While still in existance this group is now moribund in spite of founding roots of the great Senator Paul Douglas.

Chicago alone accounts for one-fourth of the state’s total population, and the Chicago metropolitan area accounts for two-thirds. Democratic-controlled Chicago and Democratic-leaning inner suburbs within Cook County comprise 43% of the total state population, and gave John Kerry a stunning county-wide vote margin of nearly 800,000 votes. Because of this, Illinois is generally considered a blue state."

Chicago has a very strong Democratic Party "machine" made infamous by the days of the late mayor Richard J. Daley and dating at least to Anton Cermak (who took a bullet meant for Franklin D. Roosevelt) in the early 20th century. Although the machine has supposedly been busted, Chicago's Democrats, led in part by the current mayor, Richard M. Daley, son of Richard J. Daley) have a virtual lock on city politics, and their get-out-the-vote efforts can be impressive. City politics have the usual divisions: racial and ethnic groups, downtown vs. the neighborhoods, old guard vs. independent liberals, but most debate takes place within a one-party, almost feudal system of a king and fifty lords (the aldermen, with their wards).

The same can be said for many of the Chicago suburbs, particularly Cicero or west-suburban DuPage County, except that these suburbs have Republican rather than Democratic machines. Both Chicago and the suburbs have a long history of political corruption, and it is common for the local governments to be under investigation by the FBI. In recent years, demographic changes have remade many inner-ring suburbs of Chicago as reliably Democratic, while outer-ring suburbs and exurbs (the "collar counties" surrounding Cook) remain Republican.

Dennis Hastert, former Speaker of the House, hails from the 14th District located in the Chicago Suburbs. His controversial mid-term resignation in 2007 following the 2006 midterms and the loss of his speakership is part of the reason the 14th district is currently represented by Democrat Bill Foster.

Henry Hyde, who led the House managers in the impeachment trial of Bill Clinton, represented Illinois's 6th District, located in Chicago's western suburbs, from 1967 until his death in November of 2007.